Typical failures of V-belts and their reasons




Type of failure

Probable reasons

 Belt rapture after short period of operation
  • belt tearing during mounting on pulley
  • drive blockage with respect to failure of driven machine or foreign body entrapped inside the drive
  • poorly calculated drive with too small number of belts (poorly calculated coefficient of conditions of operation kT)
One-side usage of belt at its side wall
  • too big not-parallelism of belt pulleys axis
 Earlier usage of side surfaces at whole length of belts
  • too big torque (mainly for drives with big start-up torque during driving machine start-up and big resistance torque during start-up of driven machine is necessary to use equipment ensuring soft start)
  • improper angle or excessive usage of groove of pulley
  • too small belt tension
  • too often short-term overloads of gearing with respect to failure of driving machine
  • too small number of belts
  • lack of parallelism of belt pulleys setting
  • minimal pulley diameter is exceeded
  • surface of grooves possess to big roughness
Local usage of side surfaces
  • too small belt tension
  • blockage of driven machine pulley with respect to bearing failure
 Grooves at side surface at whole belt length
  • belt friction because with contact with part of a machine
  • belt works in used-up groove of pulley
  • improper groove cross-section
 Transversal belt breakage at the bottom side
  • usage of external tension roller instead of internal
  • too small diameter of tension roller
  • excessive or too small temperature of operation
  • too big slippage
  • chemical influences
  • excessive belt tension
 Indurations and ruptures of a wrap
  • strong influence of dust
  • too big ambient temperature
  • influence of chemicals
 Strong vibration
  • base of axle bigger then is recommended
  • big shock load
  • too small belt tension
  • non balanced grooved pulleys
  • overloaded drive
  • angle of groove is not correct
Twisting of belts
  • lack of coaxiality in pulleys setting
  • not correct belt or groove profile e
  • excessive vibration
  • too small belt tension
  • penetration of foreign material into grooves
  • overloaded drive
 Falling of belts from pulleys after short period of operation
  • too small belt tension
  • too small frequency of control and adjustment of belt tension
Too loud operation of gearing
  • belt pulleys are not set coaxial
  • too small belt tension
  • overloaded drive
  • grooved pulleys not balanced
 Uneven belts stretching
  • faulty belts grooves
  • used belts do not create a set of belts
  • a few belts from a belt unit were replaced by new ones
  • unit of belts composed of from belts of different producers
  • bearings not lubricated

 Excessive heating of bearings

  • grooved pulleys not balanced

 Lowering of speed of driven pulley

  • check relationship between diameters of pulleys and their speeds
  • too small tension
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